Is the wood part ceiling joist

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per wiki,

A joist is a horizontal structural member used in framing to span an open space,

often between beams that subsequently transfer loads to vertical members.

This tutorial mentions ceiling joist.

Is the wood part pointed out by red arrow (img_1) the ceiling joist?

enter image description here

consider the following image (img_2), is the part pointed out by blue arrow a ceiling joist, the red one another ceiling joist?
enter image description here

Consider the following image (img_3), which comes from wiki.

enter image description here

there are 2 lay of joists, one is for ceiling, the other is for floor, is my understanding right?

Best Answer

Yes that is a ceiling joist if that is in a room over your head. If there is another space above that as another floor then that it probably also serves as a floor joist as well.

It is somewhat conventional to refer to the joists seen overhead in a basement as just the floor joists for the first floor that caps the basement.